Your stands and jack should be adequate, I mean the entire car doesn't weigh 4,000lbs. Although you might want more stands for redundancy, I use cinder-blocks (CMU if you're a Civil engineer) and stacked wood in addition to stands.

Don't take my word for this, if you don't feel safe or comfortable don't ever crawl under. And make absolutely sure the car won't roll or shift. I don't think there is one end all be all procedure, it can be done safely a variety of ways.

If you're worried about supporting the tranny pan, you could go off the transmission mount. You have to take the cross member off first. I'm assuming the 123 is similar to the 124 in this respect.

Yes, your jack and stands should be sufficient. As mentioned, redundancy is the key. I usually poke the spare tire under there as well. Even if 2 jackstands and a hydraulic jack fail (highly unlikely for all 3), the spare tire will keep you from being crushed.

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

perhaps this is redundant, but the reason the wheel(s) must be off the ground it so they are free to turn, you will need to rotate the Drive Shaft in order to remove all the nuts and bolts. perhaps one wheel will do but probably best to have both free to rotate so you don't have any trouble getting access.

The trans in neutral will let you rotate the front half.

Be sure to use something durable to mark the shaft when/if you separate it for the carrier bearing, off by one tooth can really vibrate quite a bit. I used Sharpie and it rubbed right off before I could reassemble.

__________________
1983 240d 5Sp SOLD
1986 300D(LUCO) SOLD
1983 300TD(dreamboat)SOLD
1984 240d (Executive)SOLD
1984 240d (Euripides) SOLD
1982 300sd SOLD
1982 300sd (Ambas)SOLD

Well see, if the only reason to have the car on jack stands is to turn the wheels, I don't understand why you can't have the car on ramps and jack a wheel up temporarily to rotate the drive shaft. I tested it. I can easily turn one wheel with the other on the ground, and the drive shaft rotates.

Anyway, as a test I just grabbed my trusty little jack and jack stands and proceeded to lift the car. I had both front wheels chocked.

A nuisance is the fact the handle for my jack is quite short, so jacking it up takes a long time, as it hits the fuel tank so I can only move it about 1/3rd up and down. As the car is going up it creates more space and it goes faster.


Anyway, I got it as high as my jack will go, put the jack stands underneath the sub frame, slid some rims with 4x6's on top underneath the car and crawled underneath.



And this is what I feared: I don't have enough space. I'm not a large man, but with this height I can't get to the front flex disc. I have the car on my chest by the time I've made it to the middle of the car. No space to work.

So, I need to be able to jack the car up much higher.

My current jack has a lift height of 15 1/2" inches. What kind of jack do you guys use? How high does yours go?

Alternatively I could put a 4x6 between the jack and the diff to gain a few extra inches, but I don't know if that's a smart idea?

I'm thinking I should see if I can find a 21" jack at the minimum. If I would use a 4x6 between the jack and the diff, that would be an additional 10" over what I've got now. I'd think that would be high enough (though still a little claustrophobic), so I was just curious what you guys use to lift your w123's with.

My budget for a jack would be between 150-200, and I'd like to pick it up in one of the few stores we have here, as I want to get this done this weekend and don't want to wait for an online shipment to finally get here.

Funny observation: when I spin the drive shaft, only the passenger rear wheel turns. I would've thought both would spin when they're off the ground? Spinning the drivers side wheel makes the drive shaft turn though, so it's all connected.

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__________________
"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)

I dug a trench out back for mine. That way I could have as much room as I wanted and it would be impossible for it to be dangerous. Not everyone can do that though, I realize.

-Rog

Yeah, not an option for me. The previous house I lived in had a garage with an inspection pit. It was awesome. Oil changes were a breeze, as was everything that did not need to have the wheels taken off. I'd like to meet whoever build that house and garage and take him out for a beer.


Alas, we have since moved, so no more inspection pit. Time to get a better jack...

__________________
"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)

Well, there's a good suggestion in this thread:

Rear: Where to jack it up?

I'd probably go with the concrete slabs if I didn't have the trench.

-Rog

The cribs? Yeah, that looks pretty sweet. Wouldn't know where to pick them up though.

I was thinking, I could maybe put the front end on ramps, and jack up the rear end to where it's level and set it on jack stands.

Apparently one of the big auto chain stores here in town sells a 21" high jack for 140 bucks. I think I'll go and pick that up tomorrow, plus an extra set of 3-ton jack stands. If I have four jack stands in place, plus the big 6x4's underneath the car, I really am not afraid it's going to fall on me.

It's not the safety that worries me. It's figuring out how high I need to get the car to comfortably get to everything.

__________________
"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)

You are experiencing a common problem with many a Mercedes chassis where it isn't particularly clear where it is the best place to lift or the best place to support (until you've done it before)...

...firstly the inclination to lift under the differential is not a great move on the W114/115 W123 W126 chassis types because lots of weight gets put through the "third" subframe mount that is attached to the back of the differential. On an old mount this can accelerate the end of the usefulness of the part.

On a non rusty chassis the best way of lifting is to use the jacking holes that would be used by the emergency jack. Utilising these holes allows you to lift the vehicle "from the side of the vehicle" so you can then with ease place an axle stand underneath.

I have done this many a time with the crappy changing your wheel in an emergency jack and lifted each corner of the vehicle slowly - supporting each lift movement with something sturdy like lumps of old oak (!) or jack stands. It takes a long time but it allows you to safely raise the vehicle. I always raise from one axle side to the other - across the width of the vehicle.

If you have a rusty chassis then things can get a bit more complicated as to use the jacking holes will probably result in the immediate necessity of welding! In this case I have used large bits of thick OSB / sheet material to spread the load of a lifting jack under the trailing arms - this is less than ideal but can be used in a pinch. You have to be very careful doing this as the angle of the trailing arms can work against the position in which a trolley jack is placed under the vehicle. A twisting force on those cheapo trolley jacks (like the one in your picture - sorry chap I have several of these crappy trolley jacks too!) is very dangerous.

In summary - lifting a Mercedes Benz is not as straight forward as many might expect. There are several threads out there showing the inventiveness and craziness of people. See for example

Jacking and Jack Stand Positions - Mercedes-Benz Forum

On a quality w123 - danger of using rocker lift points?

Some good advice here

PeachPartsWiki: Replacing the Differential

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

There is a lot of conflicting information out there, then. I was under the impression that jacking up on the diff was a good method.
I jacked up on the diff, and I put the stands underneath the sub-frame mount points.

IFixIt: Mercedes W123 Jack Technique

It felt quite sturdy. I shoved the car but couldn't move it, and at no point did it feel like I was stressing or breaking anything by jacking on the diff and supporting the jack stands there.

The original jack points feel a bit scary to me. My front ones are slightly rusty. The rear ones seem fine, but I'd still be hesitant.

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__________________
"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)

It looks like you may need to do a two-stage lift. You could start with the ramps then raise it from there. The vehicle jack could be used on the front to raise each side and then place the jackstand under the jack point area. This should give you enough clearance to get to the front flex disc. Do it in increments to keep things stable.

Before I bought a floor jack, I had to go through the same routine of jacking, shims and rejacking. Now I have a floor jack but no concrete floor so I have to place plywood under the floor jack to get the wheels to roll under the jack. The key to this was to do it in small stages to keep things from becoming unstable. It can be done but it takes a lot more time.

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

As an alternative place to the point under the sill jacking points I guess directly under the big bolt that holds the subframe place is (more or less) suitable. Make sure you don't get too much weight along this stiffener bracket though because they can bend and then they pull the whole end of the floor pan out of shape (where there is also likely to be rust)...

...padding under these bolts is in my opinion preferable rather than using direct contact with an unforgiving jack stand. For this I often use cheapo 2"X1" soft wood. The wood will crack and compress but it kind of forms itself to the contours and ends up being very stable after the first crush (first crush is the deepest - baby I know)...

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

I'm dreaming of a two post lift in my very near future!

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

A lift would be awesome. Back when I lived in Holland, a buddy of mine had a lift that worked on compressed air to go up, then locked into place (so the compressed air wasn't keeping it lifted). It was pretty awesome, but because of the way it was shaped it restricted access to the bottom of the car. Still though, very handy for doing brake jobs etc. I think it's called a pit lift.

Anyway, I've been thinking about it and the more I think about it, the more I would like to have the whole car raised, instead of just one end.
I was thinking something like this might work:

(Source: Zhome.com - JackUpCar)

I might run over to Home Depot tomorrow and get some wood and make four of those things. Doesn't look too complicated. I can then lift the front and back and set them on those four things. If I make them 10" high or so, that should give enough space, and still be close enough to the ground to jack up a rear wheel to rotate the drive shaft.

Same idea as using the cribs, it would just be a lot cheaper to make my own I guess. I would just cut the 8x2" pieces to size, and stack four or five on top of each other, with screws to hold them down so they don't slide.
it should be plenty sturdy. If I make 4 of those and buy a 21" jack, I think I'd be set.

EDIT:
Oh right, the point was to get the rear suspension to dangle, as someone here mentioned it would be hard to remove the drive shaft with the suspension under load. So never mind about the cribs I guess. I'll just get 3 ton jack stands and a new jack today, just jack it up as high as it'll possibly go.

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__________________
"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)

OK, I just bought a 3" ton jack with 21" lift height, and 3 ton jack stands that have a wider base then my 2-ton, and should be a bit more stable. Hopefully I'll get enough reach with this.

__________________
"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)